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The structure and catalytic properties of Rh-doped CeO2 catalysts

Abstract

The average and the local structure of nanocrystalline Rh-doped CeO2 catalysts, prepared by a co-precipitation method, were studied using a set of structural (PDF, HRTEM, XRD) and spectral (XPS, Raman spectroscopy) methods. The samples with Rh content less than 10wt.%, calcined at 450°C, were homogeneous solid solutions. A comparison of the experimental results and Pair distribution function (PDF) modeling data showed that Rh3+ substitutes Ce4+ ions in the fluorite phase. The charge equilibrium is obtained by the oxygen vacancy for each Rh3+ cation introduced into the ceria cell. The solid solution demonstrated high catalytic activity in the low-temperature CO oxidation (LTO CO). The solid solutions were stable only in a nanocrystalline state and decomposed upon thermal treatment. The calcination of the solid solution at T>450°C results in a decrease in the catalytic activity that is accompanied by Rh association in the subsurface area and strong distortion of the anionic subcell. At T=800°C α-Rh2O3 nanoparticles are formed on the surface of the fluorite phase. The XRD-detectable Rh oxide phases are formed after calcination at 1000°C. However, some part of Rh within the subsurface RhxCe1-xO2-δ solid solution remains and it preserves catalytic properties for low-temperature oxidation.

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Publication details

The article was received on 26 Sep 2017, accepted on 08 Nov 2017 and first published on 09 Nov 2017


Article type: Paper
DOI: 10.1039/C7CP06573F
Citation: Phys. Chem. Chem. Phys., 2017, Accepted Manuscript
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    The structure and catalytic properties of Rh-doped CeO2 catalysts

    E. A. Derevyannikova, T. Yu. Kardash, L. S. Kibis, E. M. Slavinskaya, V. Svetlichnyi, O. A. Stonkus, A. S. Ivanova and A. I. Boronin, Phys. Chem. Chem. Phys., 2017, Accepted Manuscript , DOI: 10.1039/C7CP06573F

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